In order to configure email alerts you need to configure this in your NP Server configuration log settings.
Go to the link:
In the sub section
Log Settings: Log Files and Notification alerts
And select 'failure' only.
'success' will send an email for every successful NP server task that has run
'warning' will send warning messages such as 'verify filter' messages or 'condition not met' messages. These are not errors but rather information only.
You must set up your email setting for email to work as well.
Make sure the select notification alert is check within your report task as well.